I'm trying to seal 2 sightglasses on an old R22 receiver. I wonder if anybody has any advice on this. I attached some photos of the receiver. The order I found the parts of the sightglass are as follows: On the bottom there is the black rubber o-ring (in the photo showing the sightglass casing), then above it is the sightglass then a fabric ring and then the threaded cap (all shown in one photo and a couple individual photos). This receiver is date stamped 1972 and made by Globe Ice Machine Inc of Los Angeles. They don't exist anymore, I checked. The assests were bought and sold and there is no more information available about this unit. I also tried to use some Gore-Tex rope to seal it and it still did not work. I'm trying to test it to 350psi which is what the relief valve is rated at. I get leaks at about 225psi nitrogen.
Does anybody know of a material that will work for this? Any ideas are appreciated.